In Leibniz we can already find the striking observation....

“ In Leibniz we can already find the striking observation that *cogitatur ergo est* is no less evident than *cogito ergo sum*. Naturally, *est* here does not mean existence or reality but being of whatever kind and form, including even ideal being, fictive being, conscious-being [*Bewusst-Sein*], etc. However, we must go even beyond this thesis of Leibniz. The correlate of the act of *cogitatio* is not, as Leibniz said, being simply, but only that type of being we call "objectifiable being." Objectifiable being must be sharply distinguished from the non-objectifiable being of an act, that is, from a kind of entity which possesses its mode of being only in performance [*Vollzug*], namely, in the performance of the act. "Being," in the widest sense of the word, belongs indeed to the being-of-an-act [*Akt-Sein*], to *cogitare*, which does not in turn require another *cogitare*. Similarly, we are only vaguely "aware" of our drives [*Triebleben*] without having them as objects as we do those elements of consciousness which lend themselves to imagery. For this reason the first order of evidence is expressed in the principle, "There is something," or, better, "There is not nothing." Here we understand by the word "nothing" the negative state of affairs of not-being in general rather than "not being something" or "not being actual." A second principle of evidence is that everything which "is" in any sense of the possible kinds of being can be analyzed in terms of its character or essence (not yet separating its contingent characteristics from its genuine essence) and its existence in some mode. With these two principles we are in a position to define precisely the concept of knowledge, a concept which is prior even to that of consciousness. Knowledge is an ultimate, unique, and underivable ontological relationship between two beings. I mean by this that any being A "knows" any being B whenever A participates in the essence or nature of B, without B's suffering any alteration in its nature or essence because of A's participation in it. Such participation is possible both in the case of objectifiable being and in that of active [*akthaften*] being, for instance, when we repeat the performance of the act; or in feelings, when we relive the feelings, etc. The concept of participation is, therefore, wider than that of objective knowledge, that is, knowledge of objectifiable being. The participation which is in question here can never be dissolved into a causal relation, or one of sameness and similarity, or one of sign and signification; it is an ultimate and essential relation of a peculiar type. We say further of B that, when A participates in B and B belongs to the order of objectifiable being, B becomes an "objective being" ["*Gegenstand"-sein*]. Confusing the being of an object [*Sein des Gegenstandes*] with the fact that an entity is an object [*Gegenstandssein eines Seienden*] is one of the fundamental errors of idealism. On the contrary, the being of B, in the sense of a mode of reality, never enters into the knowledge-relation. The being of B can never stand to the real bearer of knowledge in any but a causal relation. The *ens reale* remains, therefore, outside of every possible knowledge-relation, not only the human but also the divine, if such exists. Both the concept of the "intentional act" and that of the "subject" of this act, an "I" which performs acts, are logically posterior. The intentional act is to be defined as the process of becoming [*Werdesein*] in A through which A participates in the nature or essence of B, or that through which this participation is produced. To this extent the Scholastics were right to begin with the distinction between an *ens intentionale* and an *ens reale*, and then, on the basis of this distinction, to distinguish between an intentional act and a real relation between the knower and the being of the thing known." ―from_Idealism and Realism_ ”

Max Scheler

From : Selected Philosophical Essays